U.S. patent number 4,434,832 [Application Number 06/477,452] was granted by the patent office on 1984-03-06 for room temperature curable tire patch.
This patent grant is currently assigned to The Firestone Tire & Rubber Company. Invention is credited to William W. Barbin, Russell W. Koch.
United States Patent |
4,434,832 |
Koch , et al. |
March 6, 1984 |
Room temperature curable tire patch
Abstract
The repair of a reinforced elastomer article having a hollow
therein relates to utilizing an amine curable polymer or prepolymer
and a cured elastomer patch. The hollow in the elastomer, which can
extend either partially or completely through the article, is
filled with a gum rubber which is thereafter cured by conventional
means, such as with spotters. The area beneath the now filled
hollow is coated with a treating agent, followed by the amine
curable polymer or prepolymer and a cured patch. The polymer is
then cured at room temperature. One area of use is in the repair of
tires.
Inventors: |
Koch; Russell W. (Hartville,
OH), Barbin; William W. (Massillon, OH) |
Assignee: |
The Firestone Tire & Rubber
Company (Akron, OH)
|
Family
ID: |
23895969 |
Appl.
No.: |
06/477,452 |
Filed: |
March 21, 1983 |
Current U.S.
Class: |
152/370; 152/367;
156/95; 427/140; 152/371; 156/97; 428/63; 264/36.14 |
Current CPC
Class: |
B29C
73/10 (20130101); B29C 73/06 (20130101); C08J
5/12 (20130101); C08J 7/126 (20130101); C08J
2321/00 (20130101); Y10T 152/10918 (20150115); Y10T
152/10909 (20150115); Y10T 152/10882 (20150115); B29L
2030/00 (20130101); Y10T 428/20 (20150115) |
Current International
Class: |
C08J
5/12 (20060101); C08J 7/00 (20060101); C08J
7/12 (20060101); B60C 021/00 () |
Field of
Search: |
;156/97,95,307.3,315
;427/140 ;152/367,371,370 ;428/63 ;264/36 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
"Room Temperature Vulcanizing Adhesive Based on
Ethylene-Propylene-Diene Terpolymer," Cantor, Uniroyal, Paper No.
18, 10/10/73, Hughson Chemical Division, Lord Corporation, Products
TS-2682-71..
|
Primary Examiner: Lesmes; George F.
Assistant Examiner: Schwartz; P. R.
Attorney, Agent or Firm: Hall; Daniel N.
Claims
What is claimed is:
1. A repaired elastomer article, comprising:
the elastomer article, said article having a hollow therein;
a cured gum rubber disposed within the said hollow and filling it
thereby;
a treating agent applied to the inner surface of said article
immediately surrounding said filled hollow, said treating agent
selected from the group consisting of: N-halohydantoins,
N-haloamides, N-haloimides, and combinations thereof;
an amine curable polymer or prepolymer applied over the treated
surface of said article; and
an elastomeric patch positioned over said polymer or
prepolymer;
wherein said polymer of prepolymer is cured in situ at room
temperature wherein said patch has a coating of the treating agent
on its inner surface; and
wherein said elastomer article is cured and unsaturated.
2. A repaired elastomer article according to claim 1, wherein said
article has cords therein, and wherein said patch has cords
therein.
3. A repaired elastomer article according to claim 2, wherein said
amine curable polymer or prepolymer is selected from the group
consisting of epoxy resins, halogen-containing hydrocarbon
polymers, chlorosulfonated polymers, polymers containing acid
halide groups, or haloformate groups, polymers containing anhydride
groups which, on reaction with diamines, yield amide acid linkages,
organopolysiloxanes, urethane polymers or prepolymers and
combinations thereof; and
wherein said treating agent is selected from the group consisting
of 1,3-dichloro-5,5-dimethylhydantoin,
1,3-dichloro-5-methyl-5-isobutyl hydantoin,
1,3-dichloro-5-hexylhydantoin, N-bromoacetamide,
tetrachloroglycoluril, N-bromosuccinimide, and mono, di, or
trichloroisocyanuric acid.
4. A repaired elastomer article according to claim 3, wherein said
ambient temperature cure of said amine curable polymer or
prepolymer occurs at a temperature of from about 10 degrees C. to
about 50 degrees C.
5. A repaired elastomer article according to claim 4, wherein said
treating agent is selected from the group consisting of
monochloroisocyanuric acid, dichloroisocyanuric acid,
trichloroisocyanuric acid and combinations thereof.
6. A repaired elastomer article according to claim 5, wherein said
amine cured polymer or prepolymer is said urethane polymer or
prepolymer.
7. A repaired elastomer article according to claim 5, wherein said
patch contains at least 70 % by weight of natural rubber.
8. A repaired elastomer article according to claim 7, wherein the
strength of cords in said patch is approximately equal to the
strength of cords in said elastomer article.
9. A repaired elastomer article according to claim 7, wherein said
elastomer article is a tire.
10. A process for repairing an elastomer article having a hollow
therein, comprising:
filling the hollow with a gum rubber;
curing said gum rubber;
applying a treating agent to the inner surface of the article
immediately surrounding the filled hollow;
applying a quantity of amine curable polymer or prepolymer over the
treated surface of said article;
applying a treating agent to the surface of an elastomeric patch
and positioning said patch over said polymer or prepolymer; and
curing said polymer or prepolymer at room temperature;
wherein said treating agent is selected from the group consisting
of: N-halohydantoins, N-haloamines, N-haloimides, and combinations
thereof.
11. A process according to claim 10, wherein said article has
previously been cured, and wherein said patch has previously been
cured.
12. A process according to claim 11, wherein said article has cords
therein and wherein said patch has cords therein.
13. A process according to claim 12, wherein said amine curable
polymer or prepolymer system comprises a polar solvent, amine
curable polymer or prepolymer and an amine curing agent, said polar
solvent having a dipole moment in excess of 0.4 Debye in which
there are no more than a total of 8 methyl, methylene or tertiary
carbon radicals per polar group contained in said compound, and
benzene and biphenyl; and said amine curable polymer or prepolymer
is selected from the group consisting of: epoxy resins, halogen
containing hydocarbon polymers, chlorosulfonated polymers, polymers
containing acid halide groups and haloformate groups, polymers
containing anhydride groups which, upon reaction with said
diamines, yield amide acid linkages, organo polysiloxanes, and
urethane polymers or prepolymers.
14. A process according to claim 13, wherein said treating agent is
selected from the group consisting of
1,3-dichloro-5,5-dimethyl-hydantion,
1,3-dichloro-5-isobutyhydantoin,
1,3-dichloro-5-methyl-5-hexylhydantoin, N-bromoacetamide,
tetrachloroglyclouril, N-bromosuccinimide, and mono, di, or
trichloroisocyanuric acid, and wherein said ambient temperature
cure is at a temperature of from about 10 degrees to about 50
degrees C.
15. A process according to claim 14, wherein said treating agent is
selected from the group consisting of monochloroisocyanuric acid,
dichloroisocyanuric acid, trichloroisocyanuric acid, and
combinations thereof, and wherein said polar compound ranges from
about 2 to about 40 parts per 100 parts of said prepolymer or
polymer and is selected from the group consisting esters, ketones,
ethers, halogenated hydrocarbons, tertiary amines, nitrile
paraffins, fully substituted amides, sulfones, sulfoxides and
sulfides.
16. A process according to claim 15, wherein said amine curable
polymer or prepolymer is said urethane polymer or prepolymer, and
wherein said patch contains at least 70% by weight of natural
rubber.
17. A process according to claim 16, wherein said polar solvent is
selected from the group consisting of dimethylformamide,
tetrahydrofuran, cyclohexanone, ethyl acetate, methyl ethyl ketone,
and acetone, and wherein said amine curing agent is selected from
the group consisting of (a) 4,4'-methylene bis (2-chloraniline),
(b) a complex of 4,4'-methylene dianiline and a salt, said salt
being selected from the group consisting of sodium chloride, sodium
bromide, sodium iodide, sodium nitrite, lithium chloride, lithium
bromide, lithium iodide, lithium nitrite, and sodium cyanide, (c) a
complex of racemic 2,3-di-4 (aminophenyl) butane with a salt, said
salt selected from the group consisting of sodium chloride, sodium
bromide, sodium iodide, potassium chloride, potassium bromide,
potassium iodide, cesium chloride, cesium bromide, and cesium
iodide, the ratio of said dianiline or said butane to said salt in
said complex being 3 moles to 1 mole, the equivalent amount of said
curing agent based upon said prepolymer or polymer ranging from
about 0.85 to about 105.
18. A process according to claim 16, wherein said elastomer article
is a tire.
19. A process according to claim 17, wherein said elastomer article
is a tire.
Description
TECHNICAL FIELD
The present invention relates to a composition and method for
repairing reinforced elastomer articles having a hollow therein,
such as for example a puncture in a tire. More specifically, the
present invention relates to the utilization of a patch in
association with the elastomer article and an amine curable polymer
or prepolymer which is curable at ambient temperatures and which
acts as an adhesive agent.
BACKGROUND ART
Heretofore, reinforced rubber articles such as tires having a cut
or opening therein have been repaired with a patch. Generally the
opening is first filled with an uncured gum rubber which is
thereafter cured by such means as portable heating units or
spotters. If required, a patch is applied to the inner surface of
the tire or other article. Usually such a patch is needed if the
reinforcing materials in the article, primarily cords or belts have
been partially or completely severed, providing a weakened area
prone to subsequent failure. In providing a patch reinforced to the
same degree as the amount of lost reinforcement, the repaired
article is, at least in theory, as strong as before the injury.
Prior art patches fall into two classes, the chemical cure patches
which are high in cost and provide only poor adhesion to the
substrate and uncured patches which require the use of heat for
proper cure and adhesion. Unlike the method of heat application for
the gum rubber filler, a rather sophisticated process must be used
to cure this latter type of patch, to wit, a tire mold or similar
device. Thus when a patch is required, on the spot or in situ
repair is exceedingly cumbersome at best and in most cases
impossible, requiring the article to be returned to the shop.
The present invention utilizes a cured rubber patch secured to the
elastomer substrate through an adhesive system which is curable at
ambient temperatures. There is therefore no need for the use of a
tire mold to effect repair and the article can easily and quickly
be treated in the field, saving both time and expense. The adhesive
system utilizes an amine curable polyurethane or other prepolymer
and a treating agent.
Considering the prior art, U.S. Pat. Nos. 3,755,261 to VanGulick;
3,888,831 to Kogan; 3,834,934 to Broisman; 3,644,256 also to
Broisman; and 3,718,587 to Bhakuni relate to amine curable curing
agents, amine curable polymers, or R.F.L. type adhesives. However,
these patents lack any suggestion of applicants' treating agent or
repair of an elastomer article.
U.S. Pat. No. 3,779,794 to DeSantis relates to a moisture-curable
polyurethane sealant primer system, whereas U.S. Pat. No. 4,085,283
to DenOtter relates to flame retardants utilized in cyanuric acid
derivatives. Hughson Chemical Division, Lord Corporation, Product
No. PS-2682-71 relates to a surface primer for elastomeric
substances utilizing a proprietary compound thought to be mono- or
dichloroisocyanuric acid. An article entitled "Room Temperature
Vulcanizing Adhesive Based on Ethylene-Propylene-Diene Terpolymer,"
Cantor, Uniroyal, Paper No. 18, presented to the Division of Rubber
Chemistry of the American Chemical Society, Denver, Colo., Oct. 10,
1973 relates to various oxidants which effect ambient temperature
cures of E.P.D.M.
U.S. Pat. No. 4,136,219 to Oldam relates to a polyurethane paint
which is applied to vulcanized rubbers. British Pat. No. 1,352,645
relates to a polyurethane paint which is app1ied to vulcanized
rubbers.
U.S. Pat. No. 4,125,522 to Becker relates to a polyurethane
adhesive, whereas U.S. Pat. No. 3,966,530 to Cutts relates to
triazoline diones which are utilized in lieu of chlorinated or
halogenated donors for treating elastomeric surfaces to improve
adhesion.
U.S. Pat. No. 4,143,454 to Utsonomiya relates to a method of
attaching connecting parts of an offshore structure wherein a
liquid rubber is applied over a treating solution which may contain
a halogen molecule. As such, this reference lacks applicant's
treating agent as well as repair of an elastomeric article having a
patch thereon.
U.S. Pat. No. 4,158,378 to Pearson relates to a cured rubber tire
having a specific polyurethane therein and to a chlorine water
treatment. Hence, Pearson also fails to teach or suggest
applicant's recited treating agent as well as the patched
article.
British Pat. No. 1,352,645 relates to N- halogen sulfonamide
treating agents which halogenize surfaces of synthetic and/or
natural rubbers.
U.S. Pat. No. 3,991,255 to Blaskjiewicz relates to the adhesion of
a polyurethane to an EPDM surface utilizing various adhesives,
however, Blaskjiewicz does not use his treating agent to form a
treating layer and utilizes elevated temperatures.
U.S. Pat. No. 4,300,970 to Honda does not disclose amine curable
resins or an ambient temperature cure.
U.S. Pat. No. 4,240,852 to Gomberg relates only to the use of a
cyanoacrylate adhesive.
U.S. Pat. No. 4,352,704 to Williams relates to applying tire tread
to a tire. This patent lacks any suggestion of applicant's treating
agent or the repair of a tire aperture.
U.S. Pat. No. 4,327,138 to Hausch fails to disclose a cured rubber
patch in repairing a rubber article.
One prior art method of repairing a tire article relates to the
utilization of a proprietary compound thought to be a mixture of
rubber and accelerators which is applied to the aperture and then
cured. In general, a very poor adhesion results and heat is
required.
DISCLOSURE OF THE INVENTION
It is therefore an aspect of the present invention to provide a
repaired reinforced elastomer article having a hollow therein
utilizing a cured rubber patch and an amine curable polymer or
prepolymer.
It is another aspect of the present invention to provide a repaired
reinforced elastomer article, as above, in which the hollow extends
into or through the reinforced material and the repair is made at
ambient temperatures.
It is a still further aspect of the present invention to provide a
repaired elastomer article, as above, in which a layer of a
treating agent is positioned on the inner surface of said article
and on the cured rubber patch.
It is yet a further aspect of the present invention to provide a
repaired reinforced elastomer article, as above, wherein said
repaired elastomer article is a tire, a conveyor belt or the
like.
It is still another aspect of the invention to provide a repaired
elastomer article, as above, wherein said cured rubber patch is
located juxtaposition to said hollow.
It is yet another aspect of the present invention to provide a
repaired reinforced elastomer article, as above, wherein said patch
has one or more cords therein.
It is still another aspect of the present invention to provide a
repaired reinforced elastomer article, as above, wherein said amine
curable polymer or prepolymer is a urethane polymer or prepolymer,
and wherein said treating agent is trichloroisocyanuric acid
(trichloro-s-triazinetrione).
These and other aspects of the present invention, which will become
more apparent from the following description, are achieved by: a
repaired elastomer article, comprising: the elastomer article, said
article having a hollow therein; a cured gum rubber disposed within
said hollow; a treating agent applied to the inner surface of said
article immediately surrounding said filled aperture, said treating
agent selected from the group consisting of: N-halohydantoins,
N-haloamides, N-haloimides, and combinations thereof; an amine
curable polymer or prepolymer applied over the treated surface of
said article; and a patch positioned over said polymer or
prepolymer; wherein said polymer of prepolymer is cured in situ at
room temperature; and wherein said elastomer article is cured and
unsaturated.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 relates to a cross-sectional view showing the repair of a
reinforced elastomeric article having a hollow extending completely
therethrough, according to the present invention.
FIG. 2 is a cross-sectional view showing the repair of a similar
reinforced elastomeric article wherein the hollow extends only
partially therethrough .
BEST MODE FOR CARRYING OUT THE INVENTION
The instant invention is useful in repairing reinforced elastomer
articles wherein damage has been manifested as a chunk-out, leaving
a hollow area in the article. The injury may extend completely
through the article or only through a portion thereof, but
reinforcement, that is cords, belts, or the like, contained in the
article will have been partially or completely severed thereby
providing a weakened area.
The invention can be seen with reference to the figures. As is
readily apparent, the salient features in each are identical except
that the hollow low 120 in FIG. 2 does not extend completely
through the substrate. For the sake of simplicity, all references
to FIG. 1 shall have equal reference to FIG. 2, except for the
dimensions of the hollow, as above. Referring then to FIG. 1, the
article is generally indicated by the number 10, comprising a
substrate 13 having embedded therein a plurality of reinforcement
cords or belts 14. and a hollow 12.
The substrate 13 can be any conventional elastomer or rubber known
to those skilled in the art and having unsaturated groups therein.
For example, it can be made from conjugated dienes having from 4 to
12 carbon atoms such as butadiene, isoprene or the like. It can
also be made from natural rubber, that is, from a substance which
is obtained from various trees and plants which grow in the tropics
or desert portions of the world. Such natural rubber generally has
in excess of 90 and usually in excess of 95% of cis
1,4-polyisoprene content. The substrate may also be various
elastomeric copolymers such as those made from monomers of
conjugated dienes having from 4 to 12 carbon atoms as set forth
above and vinyl substituted aromatic compounds having from 8 to 15
carbon atoms. Examples of such vinyl substituted aromatic compounds
include styrene, alpha-methylstyrene, and the like. An example of a
specific copolymer is styrene-butadiene rubber. Naturally, other
types of rubber compounds can be utilized such as the so called
butyl rubbers, neoprene, that is polychloroprene, and the like.
The preparation of such above noted various elastomers is well
known to the art and the article in need of repair is often in the
form of a tire, especially an off the road tire, a conveyor belt,
or similar article. Regardless however of the type or nature of the
article, it is desirable to clean the surface of the hollow prior
to repair. Cleaning can take place as through a physical treatment
of the area to be repaired, for example, as through buffing or
skiving, that is, cutting or as removing a portion of the surface.
Another method involves the use of any conventional organic solvent
to remove dirt and residue. Typical solvents include acetone and
ethyl acetate.
The next step in utilizing the invention is the packing of a
quantity of uncured gum rubber 22 into the hollow 12, most
preferably from the outer surface defined as that surface of the
substrate opposite where a patch 20 is later positioned. The gum
rubber is then cured in placed using conventional means such as a
pair of heated plates, otherwise known as spotters, one applied to
the outer surface 24 and one to the inner surface of the
substrate.
The types of gum rubber which can be used are well known in the
art, being generally composed of compounds of natural rubber or
rubber blends and typically having other compounding ingredients
such as sulfur, carbon black, accelerators, and the like. A variety
of all purpose repair gums, readily available commercially, can be
used. Alternatively, one skilled in the art can readily devise a
suitable gum rubber recipe without undue experimentation.
Once the gum rubber has been cured in place, the innerside is
buffed around the now filled aperture and a treating agent 16
applied both to the substrate and the cured gum rubber surfaces,
which should of course be first cleaned as outlined above. An amine
curable polymer 18 is then applied to the inner surface after
having been first allowed to thicken or partially "set up",
resulting in an increase in viscosity to several thousand
centipoise. This results in a toothpaste-like consistency helping
hold the polymer in place while the patch is applied.
The patch, after being buffed and having received a coating of
treating agent 16, is then applied to the polymer surface. It is
thereafter temporarily taped into place and held by some form of
applied pressure, such as, in the case of a tire, a curing tube or
a plurality of sand bags. The repair is allowed to set in this
position for approximately 24 hours. The end result is a repaired
article having much better strength and durability than one
repaired according to heretofore known methods.
In the embodiment of FIG. 2, the hollow 120 in the article 100 is
in the form of a cavity wherein some cords 140 of the reinforced
article have been damaged, severed, or the like. Usually at least
25 percent of the cords have been broken or damaged and the article
is repaired utilizing a patch. Either the cavity can be filled or
the patch applied first. In repair of cavity 120, the surface is
first cleaned. The cavity is then filled with a gum rubber 220,
generally to the level of the substrate 130. Naturally, in this
operation, the cavity is located in the upper most vertical
position of the article.
The area to be patched is prepared as before by cleaning and even
buffing, in which, in either embodiment, the tie-gum layer or the
cord ply layer can be exposed. Treating layer 160 is applied to the
patch area of substrate 130 as well as to one side of the patch
200. The amine curable polymer or prepolymer 180 is then applied to
the treated side of the patch, with the patch in turn being applied
to the treated portion of substrate 130. The ends of the patch can
be taped to the substrate or held in place with a curing tube
located inside the tire. The number of cords in the patch is as
previously set forth. That is, if less than 25 percent of the cords
are damaged, the use of the patch having cords therein is optional
in that a solid rubber patch provides adequate reinforcement. When
approximately 25 to 50 percent of the cords are damaged, severed or
the like, the strength of the cords in the patch is at least equal
to the strength of such cords before being damaged. When
approximately 50 percent or more of the cords are damaged, the
strength of the cords and the patch is equal to the strength of the
total number of cords in the substrate before any injury thereto.
The repair is then cured at ambient temperature.
Suitable treating agents include the various N-halohydantoins, the
various N-haloamides, the various N-haloimides and combinations
thereof. Examples of various desirable N-halohydantoins include
1,3-dichloro-5,5-dimethyl halohydantoin; 1,3-dibromo-5,5-dimethyl
hydantoin; 1,3-dichloro-5-methyl-5-isobutyl hydantoin; and
1,3-dichloro-5-methyl-5-hexyl hydantoin. Examples of N-haloamides
include N-bromoacetamide and tetrachloroglycoluril. Examples of
N-haloimides include N-bromosuccinimide and the various chloro
substituted s-triazinetriones, commonly known as mono-, di-, and
trichlorocyanuric acids. A preferred treating composition for use
in the practice of the invention are the various mono-, di-, or
trichloroisocyanuric acids or combinations thereof.
Trichloro-s-triazinetrione (trichloroisocyanuric acid) is
especially preferred.
The treating agents usually exist in solid form. They are readily
soluble in solvents such as acetone and the like and thus can be
applied in liquid form. Application of the treating agent generally
occurs at ambient temperatures. Application can occur through any
conventional manner as through brushing, spraying, or the like. The
amount applied is such that the rubber substrate surface is coated.
Preferably, two or more coats of the treating agent or adhesive
compound are used to insure that all the cured rubber substrate
surface has been coated.
A typical amount of the treating agent in the suitable solvent, for
example ethyl acetate or acetone is generally from 0.1 to about 10%
by weight based upon the total weight of said treating agent and
solvent, and preferably from about 0.5% to about 5%. Of course
higher or lower concentrations can be utilized. This solvent system
has been found to dry within a matter of minutes so that the amine
curable polymer or prepolymer can be bonded thereto. It is thought
that the adhesive treating system adds halogen groups, for example,
chlorine to the cured rubber which activates the cured rubber
surface, allowing the amine curable polymer or polymer system to
adhere strongly to the cured rubber surface.
Of the various amine curable polymers or prepolymers, the urethanes
are preferred. Other prepolymers or polymers which can be cured
with the amine curing agent include the compounds set forth in U.S.
Pat. No. 3,755,261 which is hereby fully incorporated by reference.
Briefly, such compounds includes the various epoxy resins such as
those disclosed in the Encyclopedia of Polymer Science and
Technology, Interscience Publishers, New York (1967), vol. 6, pages
212-221; halogen containing hydrocarbon polymers such as
chloroprene polymers, chlorinated butyl rubber and chlorinated
polyethylene and polypropylene; chlorosulfonated polymers such as
those described in U.S. Pat. No. 2,723,257; polymers containing
acid halide groups such as COCl and haloformate groups such as
OCOCl; polymers containing anhydride groups which on reaction with
diamines yield amide-acid linkages, and organo-polysiloxanes as
described in U.S. Pat. No. 2,938,010.
The urethane prepolymers or polymers, that is, those which contain
isocyanate groups, are generally formed by first reacting a
polyether polyol or a polyester polyol with a molar excess of a
diisocyanate to form a prepolymer having terminal isocyanate
groups. The polymer is then cured to increase its molecular weight
from less than about 3000 upwards to over 10,000. Examples of such
polymers are set forth in U.S. Pat. Nos. 2,618,516; 2,777,831;
2,843,568; 2,866,774; 2,900,368; 2,929,800; 2,948,691; 2,948,707;
and 3,114,735 all of which are hereby fully incorporated by
reference. Typical specific examples of such polyurethanes include
Adiprene L-367 which is a polytetramethylene ether glycol
containing approximately 6.4% isocyanate end groups by weight
manufactured by DuPont; Adiprene L-42, a polytetramethylene ether
glycol containing approximately 2.8% isocyanate end groups by
weight, also manufactured by DuPont; and Cyanaprene A-7, a
polyester-based coating polymer with approximately 2.4% isocyanate
end groups, manufactured by American Cyanamid. Blends of these
polyurethanes can also be utilized. Moreover, it has been found,
particularly with repair or application of the amine curable
polymer to the patch area, that is the area between patch 20 and
cured substrate 13, better adhesion is often obtained by utilizing
two different types of urethane. For example, a urethane containing
a high amount by weight of isocyanate end groups, such as Adiprene
L-367 can be blended with urethane containing a low amount by
weight of isocyanate such as Adiprene L-42. The relative amount of
one urethane to the other can range from about 1 to about 99% and
desirably from about 30 to about 70% by weight.
To the amine curable prepolymer or polymer compound is added a
conventional amine curing agent, known to those skilled in the art.
Generally, any conventional or known amine curing agent can be used
and therefore only a few specific examples will be given. Thus, the
curing agent can be MOCA, that is, 4,4'-methylene bis
(2-chloroaniline) or desirably, a complex of 4-4'-methylene
dianiline and a salt, or a complex of racemic
2,3-di-(4-aminophenyl) butane and a salt as set forth in U.S. Pat.
No. 3,755,261 to VanGulick which is hereby fully incorporated by
reference. The methods for preparing the complexes are also set
forth therein. A preferred salt utilized with the 4,4'-methylene
dianiline compound is sodium chloride or lithium chloride. Due
generally to availability and cost, the complexes or salts derived
from 4,4'-methylene dianiline are highly preferred. Another class
of amine curing agents which can be utilized are the various
Versamides, that is, the condensation products of polyamines and
dibasic acids obtained when certain unsaturated fatty acids are
polymerized, and are manufactured by The Henkel Chemical
Company.
The equivalent weight of the curing agent utilized with regard to
the curable prepolymer or polymer, including the amine curing
agent, generally ranges from about 85% to 115% with from about 95
to 105% being preferred. Often to facilitate processing, the curing
agent and especially an amine curing agent, such as the complex of
4,4'-methylene dianiline and a salt is utilized with a plasticizer
such as dioctylphthalate (DOP) on a 50% weight basis or
tetraethylene glycol bis (2-ethylhexanoate) manufactured by Union
Carbide Corporation on a 50% weight basis under the trade name
Flexol 4GO. The amount of plasticizer can range from about 20% to
about 60 weight percent.
The curing agent is blended with the prepolymer or polymers in
various mixers such as dough mixers, high speed impellers,
paddle-type mixers, and the like. Small batches can be mixed by
stirring with a spatula. Usually the prepolymer or polymer is a
liquid. If not, when mixed with the polar solvent, a liquid mixture
results. However, even if a solid curing agent is used, when added
to the prepolymer or the polymer, and to a solvent system, a liquid
system results even though the curing agent (e.g., amine) can be in
the form of a dispersion. Thus, although the system may contain
solids therein, the solids exist in the form of a dispersion so
that a liquid system is produced.
The curing agent and the amine curable polymers or prepolymers form
the curable polymer system which is mixed with a polar solvent so
that a liquid system is obtained which cures at ambient or room
temperature, that is, the prevailing temperature is from about 10
degrees C. to about 50 degrees C. Often the ambient temperature
will range from about 15 degrees C. to about 35 degrees C. or 40
degrees C. The polar solvents which can be utilized, especially
with the amine curing agent and the amine polymers or prepolymers
are, for example, set forth in U.S. Pat. No. 3,888,831 to Kogan
which is hereby fully incorporated by reference. Such solvents
include those having dipole moments in excess of 0.4 Debye in which
there are no more than a total of 8 methyl, methylene or tertiary
carbon radicals per polar group.
Generally, the amount of solvent utilized per 100 parts by weight
of the curable prepolymer or polymer ranges from about 2 to about
40, desirably from about 2 to about 20 and preferably from about 5
to about 15 parts by weight. Specific examples of preferred
solvents include dimethylformamide, tetrahydrofuran, cyclohexanone,
ethyl acetate, nitromethane, nitroethane, nitroproprane, methyl
ethyl ketone, and acetone. Acetone and methyl ethyl ketone are
highly preferred. The amount of curing agent based upon said
polymer or prepolymer ranges from about 0.85 to about 1.15
equivalents.
Considering patch 20, it can generally be of any desired size so
long as it is greater in surface area than the hollow it seals.
Typically, the surface area of the patch is at least twice as great
as the hollow. Generally, an appropriate patch size will be known
to one skilled in the art of patch construction and/or patch
application. The patch is made of rubber and is generally fully
cured. Although cured natural rubber or a composition containing at
least 80% by weight of natural rubber is often preferred, any
conventional type of cured rubber compound can be utilized. Thus,
the patch can be made from a conjugated diene having from 4 to 12
carbon atoms, copolymers made from conjugated dienes having from 4
to 12 carbon atoms with vinyl substituted aromatics having from 8
to 15 carbon atoms, for example styrene-butadiene rubber, and the
like. In essence, the patch can be made from the same type of
rubber as the substrate. Often, the patch will have a cushioned
layer thereon to alleviate stresses formed between the tire carcass
and the patch.
Because the patch must provide structural reinforcement to the
repaired article, it generally utilizes cords in the same manner as
the article. Although the number of cords can range from a small
number to a very large number, as above, they generally equal in
strength the cords damaged in the substrate. Such a provision
provides an adequate reinforcement for the article. The cords can
be made of polyester, nylon, steel, rayon, or the like with nylon
being preferred. It has been found that according to the present
invention, large hollows can be repaired up to approximately 8
inches in diameter.
In preparing the amine curable polymer system, generally the amine
curable polymer or prepolymer is mixed with the polar solvent and
thereafter the curing agent. During cure, an effective and strong
bond is formed between the prepolymer or polymer system and the
treated elastomer substrate. Since the present invention relates to
an ambient temperature cure, repair of large and cumbersome
articles such as off the road tires, conveyor belts, and the like
can be made in situ. In other words, the repair can be made at the
job site. The only accessory which may be required is some means
for holding the patch in place while the polymer cures. As above,
this can be an inflatable bladder or one or more sand bags. Since
the cure is ambient, no steam chambers or other vulcanizing tire
repair equipment is required other than that necessary to cure the
gum rubber. This of course also results in an energy savings.
It is to be understood that various conventional additives in
typical amounts can be added to the amine curing agent and
prepolymer system such as colorants, softeners, fillers,
antioxidants, plasticizers, and the like.
The invention will be better understood by reference to the
following representative examples:
EXAMPLE 1
Sidewall Section Repair
An 11.00 R 24.5 steel radial truck tire containing two injuries in
the sidewall was repaired as follows: injury number 1 was 3/8
inches wide by 4 inches long after buffing with a tungsten-carbide
tip tool. The buffed area was cleaned with a rubber solvent. The
innerliner was then marked with an outline of the patch and
likewise buffed with the tungsten-carbide tool. Only the innerliner
was buffed. The buffed areas were cleaned again with a rubber
solvent and allowed to dry thoroughly. A coat of Firestone's
Sup-R-Tac rubber cement was applied to the buffed areas. It also
was allowed to dry thoroughly. An uncured patch was stitched into
place (Rocson 5314-6, Rocson, Inc., Copley, Ohio). Uncured
all-purpose gum rubber (Roscon regular cure AP repair gum) was then
stitched into the external injury. The repair was cured in a Vulcan
split-rim mold.
Injury number 2 was 3/8 inch wide by 31/2 inches long after buffing
with a tungsten-carbide tip tool. The cut was cleaned thoroughly
with a rubber solvent and allowed to dry. A cover patch was
cemented and stitched to the innerliner in order to hold the gum
rubber in the external injury. The cover patch, made from the all
purpose gum rubber, was about 1/2 inch larger in all directions
than the injury and about 1/8 inch thick. One coat of Firestone's
Sup-R-Tac rubber cement was applied to the injured area and allowed
to dry. Uncured all-purpose gum rubber (Roscon regular cure AP
repair gum) was stitched into the external injury and cured in a
Vulcan split-rim mold. The reinforced patch was then installed as
follows: the innerliner was buffed to the patch size, making sure
to remove the cover strip added earlier. The patch was also buffed.
The buffed areas, patch and innerliner, were cleaned with acetone
on a piece of Rymplecloth and allowed to dry. Two coats of a 3
percent trichloro-s-triazinetrione in ethyle acetate were applied
to the buffed innerliner and patch. After the primer system had
dried, a standard 50/50 kit was mixed. The composition was as
follows:
______________________________________ Adiprene L 42 150 grm.
Adiprene L 367 150 grm. Flexol 4GO 30 grm. A-side Acetone 30 grm.
Caytur 21 72 grm. B-side Black MB* 2 grm.
______________________________________ *15 parts of carbon black in
Dioctyl phthalate base.
The thoroughly mixed material was allowed to thicken to a nearly
non-pourable stage and then applied to the patch and innerliner
area. The patch was placed in position and held there with tape. A
tube was then inserted and inflated to hold the patch in position
and to apply pressure on it. The patch was cured for 24 hours at
room temperature. After the 24 hour cure period, the tape and tube
were removed. The repair had good appearance. The tire was tested
on a radial truck tire endurance test known as a C-2 test, which
loads the tire 40 percent over the rated load and runs 22 mph until
failure. The tire failed at 4455 miles yielding very good
performance for a repaired tire. As a comparison, new tires are
expected to run 7000 miles and a used tire over 3000 miles. The
failure occurred on the opposite side of the tire, away from the
two repairs. The uncured patch had fallen off of the
innerliner.
Example 2
Full Section (Crown) Repair
An 18.00.times.25,28 ply rated, off-the-road (OTR) tire containing
a 1.times.21/2 inch injury completely through the tire in the crown
area was repaired as follows: the injury was buffed clean to an RMA
#3 or #4 buff rating using a tungsten carbide tool. The innerliner
was lightly buffed 1/2 to 1 inches wider than the injury. The
buffed areas were cleaned with a rubber solvent and allowed to dry.
A coat of Firestone's Sup-R-Tac rubber cement was applied to the
buffed surface and allowed to dry. A cover patch made from uncured
all purpose gum rubber (1/8 inch thick Crocson Patch Company,
Copley, Ohio) was stitched onto the innerliner. The external injury
was then filled with the same rubber by stitching small amounts in
at a time. The spot was then cured using a Vulcan mold. After the
tire had cooled, the patch was positioned over the internal injury
and outlined. The temporary cover patch, innerliner, tie-gum and
two body plys were removed from the tire, tapering the edges of the
innerliner so that the patch made a close fit with it. The patch, a
Roco No. 4, was also buffed. All buffed areas were cleaned using
acetone and Rymplecloth. After the surfaces had dried, several
coats of a 3 percent trichloro-s-triazinetrione in ethylacetate
were applied to the innerliner area and the patch. The primer was
allowed to dry thoroughly. A standard 50/50 kit described in
example 1 was mixed thoroughly and allowed to thicken nearly to a
non-pourable stage. The material was then applied to the patch and
innerliner areas. The patch was installed and taped in place. A
tube was inflated behind the patch to hold the patch in position
and to apply pressure to it. The patch was cured 24 hours at room
temperature after which the tube and tape were removed. The repair
looked excellent. The tire was recapped and sent back into service.
The tire has not been returned after seven months, indicating that
no failure has occurred.
Example 3
Reinforce (Crown) Repair
A 33.5.times.33,44 ply rated, OTR tire requiring a reinforce patch
was repaired as follows: the weakened area of the tire was located
on the inside of the tire and marked. A template of the size of the
patch to be added was centered over the injured area and outlined.
The area was buffed with a tungsten carbide tool down to the top or
first body ply (removed innerliner and tie-gum layers). The buffed
area was washed thoroughly with acetone on a piece of Rymplecloth.
Both the patch and innerliner were then treated with several coats
of a 3 percent trichloro-s-triazinetrione in ethyl acetate. The
primer was allowed to dry thoroughly. A standard 50/50 kit
described in example 1 was mixed thoroughly and allowed to thicken
nearly to a non-pourable stage. The material was then applied to
the patch and innerliner areas. The patch was installed and taped
in place. A tube was inflated behind the patch to hold the patch in
position and to apply pressure to it. The patch was cured 24 hours
at room temperature. After the 24 hours had elapsed, the tube and
tape were removed. The repair looked very good and was tightly
bound to the innerliner. The tire was recapped, the external spot
being repaired at the time of recapping. The tire was sent back
into service. The tire has not been returned after seven months,
indicating continued use.
Generally, any rubber article having a hollow therein can usually
be repaired by the present invention. Specific examples include
conveyor belts and tires, especially off the road tires such as
those utilized for front-end loaders, mining equipment machines and
the like.
While various preferred embodiments of the present invention, as
well as the best mode thereof have been described in detail, in
accordance with the Patent Statutes, it is to be understood that
the invention is measured by the attached claims.
* * * * *